Pneumatic-cushion seat-post



No. 622,179. Patented'Mar. 28, |899. A. J. DAVIS.

PNEUMTIC CUSHION SEAT POST.

(Application led Feb. 10, 1898.)

(No Model.)

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NTTnD STATES j PATENT OFFTCE.

ANDREW J. DAVIS, OF CHICAGO, ILLINOIS.

PN EUMATIC-CUSHION SEAT-POST.

SPECIFICATION forming part of Letters Patent No. 622,179, dated March28, 1899.

Application filed February 10, 1898. Serial No. 669,842. (No model.)

T @ZZ whom t may concern:

Beitknown that LANDREW J. DAVIS, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented or discovered a new and useful Improvement in Pneumatic-Cushion Seat- Posts, of which the following is a full, clear, and exactdescription, reference being had t0 the accompanying drawings, formingpart. of this specification, in which- Figure 1 is a view in sideelevation of my pneumatic-cushion seat-post set in a bicycleframe. Fig.2 is a central vertical section on an enlarged scale. Fig. 3 is asimilar view, partly in elevation, showing the plunger depressed. Fig. 4is a view similar to Fig. 2, showing a modified construction. Fig. 5 isa plan view of Fig. 3. Fig. 6 is a cross-section taken ,on the line VIVI of Fig. 4. Fig. 7 is a partial sectional view on a further enlargedscale, showing the parts 'joined by a threaded ring. Fig. 8 isaperspective view of the diaphragm. Fig. 9 is a cross-sectiontherethrough on the line IX IX.

Myinvention relates to pneumatic cushionsupports for bicycle and otherseats, and is designed for the purpose of absorbing shock and vibration,thereby obviating the inj urious effects of riding on rough roads.

It consists of a plunger mounted in a suitable receiving-shell andcapable of a limited movement therein, the plunger in its movementacting to still further compress a contained body of compressed air orother fluid.

The details of construction by which the device is made operative andthe parts packed to prevent leakage shall now be fully described.

Referring to the drawings, 2 is the main cylindrical shell forming theupper part of the air-reservoir and provided with a downward extension 3of reduced diameter, which serves, with the shell 2, to contain the bodyof air under such pressure as is necessary to give a proper resistanceto the weight of the rider. Air is pumped into this reservoir up to suchpressure through a check-valve 4, placed in ,the side of the cylinder 2and made in a manner similar to the well-known checkvalves in use onbicycle-rims.

The reduced extension 3 is of a diameter to lit neatly within the hollowseat-post tube I shall denominate the stem, is closed and made air-tightin any desired manner.

Upon the top of the shell 2 is secured an upper cylindrical coping '7,the parts being tightly clamped together by means of bolts I, passingthrough lugs 8 8, the upper lugs and base of coping having adownwardlyprojecting peripheral bead 9, overlapping and covering thejoint.

Within the coping 7 is a plunger 10, making a neat fit, having a roundedsmooth bottom 11, and a central tube 12 of reduced diameter secured tothe bottom projects upwardly through the top of the coping with asliding iit and constitutes the seat-post proper, having alaterallyprojecting reach 13, to which the saddle is secured by clip 14in the well-known manner.

15 is a cup-shaped diaphragm of rubber, the edge of which is tightlyclamped between the shell 2 and coping 7 by bolts 1 with such force asto insure a close air-tight joint, and when in the position shown inFig. 2 and air is pumped into the reservoirv the diaphragm 15 will bepressed up tightly against the bottom 1l, forcing the top of plunger 10up against the top of coping '7. When, however, sufficient weight isimposed upon the tube 12 to overcome the air-pressure, the plunger willbe forced down to such an extent as to compress the air sufficiently toform an equalizing resistance, atwhich point the plunger andsuperimposed weight will be balanced and cushioned upon the compressedair. In the downward travel of the plunger the diaphragm 15 will bestretched over its bottom end and forms a tight packing, preventingescape of air, and by reason of the construction of the bottom 11 oers ahard unyielding resistance to the pressure of the air.

In Fig. 4 I have shown a modified construction in which the plunger IOis provided with a downward extension or stem 16, with a guiding-piston17 at the end, having air-passages 18, while a downward extension 19 ofthe coping, preferably employed in both constructions, embraces the tube12, and by these IOO In Fig. 7 I have shown another means ofv securingthe cylinder and coping together by a flanged collar 20, engaging aperipheral flange 21 at the base of the coping 7, the eollar having aninternally-threaded downward extension 22, screwed upon the reinforcedtop of the cylinder 2 by spanncr-holes 23.

24 is a ring adjustably secured upon the tube 12, which serves to limitits downward motion by coming into contact with the upper end of thecoping.

It will be seen that when thus constructed my seat-post constitutes avery compact and effective cushion for the saddle and that by reason ofthe perfect packing secured by the diaphragm its continuous resiliencyis assured, while the evils arising from stufiingboxes are entirelyovercome.

It will be understood that the post may be made in various sizes andproportions to suit requirements of use and that various changes ormodifications may be made by the skilled mechanic without departing frommy invention.

l. A pneumatic-cushion seat-post for bicycles comprising anair-reservoir, a plunger mounted therein provided with a seat-post, anintervening elastic diaphragm extending across the reservoir andconfined therein at its edges against which the plunger abuts, and areduced extension of the reservoir adapted to be mounted in the frame ofthe bicycle, substantially as set forth.

2. A pneumatic-cushion seat-post for bicycles comprising a cylindricalreservoir, a reduced cylindrical extension thereof constituting a stemadapted to be mounted in the frame of the bicycle, an upper cylindricalcoping secured upon the cylindrical reservoir, a cup-shaped elasticdiaphragm clamped between the reservoir and coping, a plunger within thecoping and a reduced extension secured to the plunger having asaddle-reach, substantially as set forth.

3. In a pneumatic-cushion seat-post for bicycles; a cylindricalreservoir provided with a valve, a hollow extension thereof adapted tobe inserted in the bicycle-frame, an upper cylindrical coping secured tothe reservoirshell with an intervening diaphragm of elastic material,and a central tube of reduced diameter projecting from the plunger upthrough the coping and provided with a saddle-reach, substantially asset forth.

4. In a pneumatic-cushion seat-post for bicycles; a plunger providedwith a saddlereach, mounted in a guiding-coping and resting on a body ofcompressed air with an intervening diaphragm of elastic material securedat its edges, and a hollow extended stem of reduced diameter adapted tobe mounted in the frame of a bicycle, substantially as set forth.

5. In a pneumatic-cushion seat-post for bicycles; a plunger providedwith a saddlereach, mounted in a guiding-coping and resting on a body ofcompressed air, with an intervening diaphragm of elastic material havingits edges confined in the coping and means for limiting the downwardmovement of the plunger, and an extended stem of reduced diameteradapted to be mounted in the frame of a bicycle, substantially as setforth.

6. In a pneumatic-cushion seat-post for bicycles; a cylindricalair-reservoir provided with a valve, a cylindrical flanged copingsecured thereon by a flanged collar screwed to the reservoir, anintervening diaphragm of elastic material having its edges confinedbetween the reservoir and coping, and a plunger mounted in the copingadapted to bear upon the diaphragm, substantially as set forth.

'7. In apneumatic-cushion seat-post for bicycles; a cylindricalair-reservoir provided with a valve, a reduced downwardlycxtend ingshell forming a part thereof, a cylindrical coping secured to thereservoir, an intervening cup-shaped diaphragm of elastic materialmaking an air-tight joint, a plunger mounted in the coping provided witha downwardlyextending stem with a ventilated guidingpiston within thereduced reservoir-shell, and an upward tube projecting through adownward extension of the coping and provided with a saddle-reach,substantially as set forth.

In testimony whereof I have hereunto set my hand.

ANDRE W J. DAVIS.

Vitnesses:

PETER J. EDWARDS, C. M. CLARKE.

IOO

